Title: Spontaneous baryogenesis without baryon isocurvature

Abstract

We propose a new class of spontaneous baryogenesis models that does not produce baryon isocurvature perturbations. The baryon chemical potential in these models is independent of the field value of the baryon-generating scalar, hence the scalar field fluctuations are blocked from propagating into the baryon isocurvature. We demonstrate this mechanism in simple examples where spontaneous baryogenesis is driven by a non-canonical scalar field. The suppression of the baryon isocurvature allows spontaneous baryogenesis to be compatible even with high-scale inflation.

This paper reviews a paradigm for baryogenesis in which the fundamental Lagrangian is baryon conserving (invariant under U(1){sub B}). At high temperatures, U(1){sub B} is spontaneously broken and an excess of quarks over antiquarks of 10{sup {minus}10}s (s {identical to} entropy density) is produced. Today, U(1){sub B} is restored. A fundamental consequence of our assumptions is that the baryon number of the Universe is constant. If initially zero, it will be zero today. The excess baryon number produced in the quark fields is exactly compensated by antibaryon number in a weakly interacting scalar particle. The authors suggest that this scalarmore » provides the mass density necessary to close the Universe.« less

We study the cosmological baryon production in two different classes of spontaneous-CP-violating models with no strong CP problem. All known realistic models predict a large ..delta..B in the range required by the observed baryon asymmetry. In the first class of models in which CP violation is transmitted from the grand-unification scale down to the low-energy sector through fermion mixing effects, baryon asymmetry arises from the nonunitarity of the transformation matrices. It is pointed out that there is no dangerous flavor-changing neutral current due to Z-boson exchanges in the Nelson-type models. Weak CP-odd interactions are mediated by colored scalars in themore » second class of models. Large matter-antimatter asymmetry can result from the decays of superheavy leptoquark scalars or from the decays of color-triplet Higgs bosons into a superheavy and light fermion.« less

We examine effects on primordial nucleosynthesis from a truly random, one-dimensional spatial distribution in the baryon-to-photon ratio ({eta}). We generate stochastic fluctuation spectra characterized by different spectral indices and rms fluctuation amplitudes. For the first time we explicitly calculate the effects of baryon diffusion on the nucleosynthesis yields of such stochastic fluctuations. We also consider the collapse instability of large mass scale inhomogeneities. Our results are generally applicable to any primordial mechanism producing fluctuations in {eta} which can be characterized by a spectral index. In particular, these results apply to primordial isocurvature baryon fluctuation (PIB) models. The amplitudes of fluctuationsmore » that are scale-invariant in baryon fluctuation (PIB) models. The amplitudes of fluctuations that are scale-invariant in baryon density are found to be severely constrained by primordial nucleosynthesis. However, when the {eta} distribution is characterized by decreasing fluctuation amplitudes with increasing length scale, surprisingly large fluctuation amplitudes on the baryon diffusion scale are allowed. {copyright} {ital 1997} {ital The American Astronomical Society}« less

We calculate the baryon asymmetry created by the decay of a pseudo Nambu-Goldstone boson (PNGB) whose interactions violate baryon number conservation. Our results are in disagreement with previous results in the original spontaneous baryogenesis models for the asymmetry produced by the decay of an oscillating scalar field with B-number-violating derivative couplings; we find that the net baryon number density is proportional to {theta}{sub i}{sup 3}, where {theta}{sub i} is the amplitude of the PNGB field in natural inflation at the onset of reheating. While our calculation of the asymmetry is carried out in the context of natural inflation our approachmore » is generally valid for baryogenesis models using decaying classical fields. We include a complete derivation of the number density of particles produced by the decay of a classical scalar field. {copyright} {ital 1997} {ital The American Physical Society}« less

It has been observed that if an extra scalar field (in addition to the inflaton) is present during the inflationary phase, its decay into thermal radiation after baryogenesis gives rise to fluctuations in the initially smooth entropy-per-baryon ratio. There was a hope that these perturbations were of the isocurvature type and that they may help explain several observed features in the large-scale structure of the Universe. We study in detail the generation of perturbations in such a two-field inflationary model. We find that the resulting fluctuations are not of the isocurvature type, but that the entropy perturbation induces a curvaturemore » fluctuation which is larger than the entropic one before the wavelengths of the perturbations enter the Hubble radius. Thus, this model is not a good candidate to provide the initial conditions for the baryon isocurvature perturbations.« less